1. Field of the Invention
This invention pertains to a dual stream filling valve. More particularly, this invention pertains to a dual stream filling valve for introducing a plurality of flowable products into a plastic container on a filling machine.
2. Description of the Related Art
Various types of filling apparatuses are known in the art. In one type of apparatus, two or more streams of, for example, liquid are introduced into a single package, such as milk and cream mixed together into a single container. Such mixing must be done in a controlled, metered manner to assure that the proper quantities and proportions of each are added to the container.
Consumers will readily recognize that milk is available having varying milk fat content, such as skim milk, "1%" and "2%" milk, as well as whole milk. The proportion of cream to milk in the final product generally controls the milk fat content. Often, cream is added to skim milk to produce the various percentages of milk fat content. This is one exemplary process in which the dual-stream filling valve can be used. In such a process, the milk is referred to as the primary fluid and the cream is referred to as the secondary fluid. It will be recognized that such an arrangement can be used for flowable product other than milk, such as dried, particulate or powdered products, as well as a combination of such solid (e.g., particulate and powdered) and liquid materials.
In one known arrangement, the combination of primary and secondary fluids in a single container is carried out using a dual-stream valve. The dual-stream valve has concentric outer and inner filling tubes (primary and secondary, respectively) that are in communication with respective liquid storage tanks or reservoirs. To meter or control the amount of secondary fluid introduced into the container, a valve element, such as a plug, is positioned at the bottom of the secondary tube. In known configurations, the plug is moved or actuated by a rod that penetrates the secondary tube, and longitudinally traverses through the inside of the tube from the tube top to the bottom where it is joined with the valve plug. As is apparent from this arrangement, the rod that traverses through the filling tube requires space or volume that could otherwise be devoted to secondary fluid flow. Moreover, this arrangement positions moving, mechanical components directly in the secondary fluid, which is typically food product. In addition, penetration of the rod through each filling tube requires the use of one or more seals to assure that the food product is fully isolated from the environs.
While such known dual-stream valves function well, they can require considerable maintenance and inspection. As will be apparent, each such seal provides the opportunity for leakage. Moreover, as noted above, such systems require space within the secondary tube, which, consequently increases the diameter of the secondary tube. Additionally, known dual-stream filling arrangements can create localized spots or locations that tend to promote undesirable accumulation of food product.
Accordingly, there continues to be a need for a dual-stream filling valve that does not impact or reduce the usable space or volume of the secondary filling tube or conversely require an increase in the diameter of the tube. Such a dual-stream valve has a minimum of moving mechanical parts that directly contact the flowable material in the system,. typically a food product. Moreover, such a dual-stream valve minimizes the number and complexity of the seals required which, in turn, reduces the opportunity for leakage into and out of the valve.